SQLFiddle: must declare the scalar variable error

问题:

I'm trying to execute next SQL statement (SQL Server 2008 Profile)

DECLARE @fun int;
SET @fun = 40;

select cast(@fun as varchar(10)) + 'hello'

and SQLFiddle gives me the error: Must declare the scalar variable @fun

Where I'm wrong?

http://sqlfiddle.com/#!3/d41d8/42156

回答1:

I think the semicolons are introducing the problem here.

As described here: http://www.sql-server-helper.com/error-messages/msg-137.aspx and here: SQL Server - Variable declared but still says "Must declare the scalar variable", the problem arises when the statements are executed individually instead of as a “unit”, and the semicolons seem to trigger that.

When I remove the semicolons from your statement, it works: http://sqlfiddle.com/#!3/d41d8/42159

回答2:

You need to select the [Go] from last dropdown.

回答3:

You dont have to remove the semicolons, the important part is select [GO] as query terminator on the bottom right conner dropdown.

FIDDLE DEMO

DECLARE @fun int;
SET @fun = 40;
select @fun;
GO

select 10;
GO

select @fun + 10;

The first three sentences are executed as a whole because now ; doesnt end the query. So @fun is visible on that scope.

Second block take notice you need leave a space after GO.

Third block wont work because @fun isn't define in this block.